BS7671:2018 DPC - Local Earth Electrode with TN systems

[securespark]

I don't really understand that. Indeed, in my TT installation, the earth electrode is inevitably connected, via boding, to utility pipes.

Sorry for the confusion. I was referring to TN systems.

 

[JohnW2]

Sorry for the confusion. I was referring to TN systems.

Yes, I realise that, but I still don't understand your comment "...you can't connect utility pipes to earth electrodes." - I was merely pointing out that, in a TT installation, such a connection is inevitable if there are extraneous-c-ps.

The new proposed reg will, of course, require that if metal utility pipes enter the property, that they must be connected (via bonding) to an earth electrode - so I wonder what you were actually trying to say.

Kind Regards, John

 

[JohnW2]

Never had you down as a conspiracy theorist.

BAS perhaps put it rather more bluntly than I did but, as I said, it is very possible that there is an (internal and/or external) requirement for a consultation process to happen, and be seen to happen. One obviously hopes that that this process will be conducted in a conscientious fashion, but it's difficult for outsiders to really know how much consideration is given to comments received.

However, as I said and implied, the members of the committee are far from stupid, and undoubtedly will already have thought of, discussed, and maybe argued about many of the points which are subsequently raised as comments by outsiders. In many cases, there is therefore probably no need for much, if any, further discussion about comments - if the committee has already been through all that discussion (and reached a conclusion) during the process of preparing the draft.

Kind Regards, John

 

[securespark]

I have got to the bottom of it now.

It's all to do with my brain.

I did not explain myself properly initially.

I meant that the utility pipe (eg gas) was connected direct to a rod, but that rod was not connected directly to anything else.

Thus inside the property you have a situation where the gas pipe (connected to the rod) is at one earth potential and the rest of the installation is at another.

Unless there is supplementary at more than one point, you could have a danger of a PD across different parts of the installation that are connected to earth.

 

[EFLImpudence]

I'm a bit lost. Why was that done?

Gas pipes are not allowed to be used as earthing or bonding conductors.

Was it someone's misguided way of bonding the pipe?
I.e. the frequent question "Should the gas pipe be earthed?".

 

[JohnW2]

I have got to the bottom of it now. ... It's all to do with my brain. ... I did not explain myself properly initially. ... I meant that the utility pipe (eg gas) was connected direct to a rod, but that rod was not connected directly to anything else. .... Thus inside the property you have a situation where the gas pipe (connected to the rod) is at one earth potential and the rest of the installation is at another.

Well, yes, that would not be allowed, but even if there were no earth rod involved, it still would not be permissible to have an incoming metal gas pipe not main bonded to the installation's MET (hence also to the rest of the installation).

If, as required, the gas pipe were bonded to the installation's MET, then also connecting it to an earth rod (which is effectively what the new reg will require) would do no harm.

Kind Regards, John

 

[flameport]

I meant that the utility pipe (eg gas) was connected direct to a rod, but that rod was not connected directly to anything else.

Was it someone's misguided way of bonding the pipe?

Sadly such things have been asked many times before.
https://www.diynot.com/diy/threads/gas-pipe-bonding.148539/
https://www.diynot.com/diy/threads/using-an-earth-rod-to-bond-gas-and-water.180330/
https://www.diynot.com/diy/threads/earth-stake.92441/

Just 3 examples of many where people considered it perfectly normal to install an earth rod just for the purpose of connecting it to a gas pipe - and those are only the few people who used this forum and thought to ask about it first.

 

[JohnW2]

Sadly such things have been asked many times before ..... Just 3 examples of many where people considered it perfectly normal to install an earth rod just for the purpose of connecting it to a gas pipe - and those are only the few people who used this forum and thought to ask about it first.

I'd forgotten that. Do I take it that you mean without any (proper, as required) main bonding to the pipe?

Kind Regards, John

 

[flameport]

Do I take it that you mean without any (proper, as required) main bonding to the pipe?

That's what the people in those examples wanted - to install an earth rod instead of main bonding, the rod purely being used to connect to the gas / water pipe and nothing else.

 

[ban-all-sheds]

That's what the people in those examples wanted - to install an earth rod instead of main bonding, the rod purely being used to connect to the gas / water pipe and nothing else.

That's what happens when a culture of tolerating people doing things without a full understanding is allowed to exist.

 

[JohnW2]

That's what the people in those examples wanted - to install an earth rod instead of main bonding, the rod purely being used to connect to the gas / water pipe and nothing else.

Hmmm. I presumed that's what you meant. That clearly suggests that the people in question had as little understanding of the concept of/reason for main bonding as apparently did whoever wrote the regulation relating to bonding of incoming supply pipes (at least in the 17th. - I haven't looked at that in the DPC yet!)!

Kind Regards, John

 

[securespark]

That's what happens when a culture of tolerating people doing things without a full understanding is allowed to exist.

You should have been a Vicar, Ban!

 

[JohnW2]

You should have been a Vicar, Ban!

Maybe However, as I've just written, he might also have made a comment about "... when a culture of tolerating people writing regulations without a full understanding is allowed to exist." !

Kind Regards, John

 

[EFLImpudence]

That clearly suggests that the people in question had as little understanding of the concept of/reason for main bonding as apparently did whoever wrote the regulation relating to bonding of incoming supply pipes (at least in the 17th. - I haven't looked at that in the DPC yet!)!

In Flameport's excellent post listing the changes he notes the draft as stating:

411.3.1.2 NEW - Metallic pipes entering the building having an insulating section at their point of entry need not be connected to the protective equipotential bonding

which it does, yet 544.1.2 - in the draft - is unchanged.


Is this something to be reported?

It seems odd that they would fundamentally change a ruling and insert the new in a regulation where it was not needed (i.e. extraneous-c-ps shall be bonded - still the case) but not alter - or place it in - the specific regulation where it wrongly states the opposite (to bond on consumer's side of insulating section).

 

[securespark]

I'd point it out to them for sure.